1. Field of the Invention
The present invention relates to a peeling member for peeling a paper from a various types of rollers installed in an electrophotographic apparatus such as a copy machine and a laser beam printer. More particularly, the present invention relates to a peeling member for use with a fixing roller required to have heat resistance.
2. Discussion of Background
Typically, electrophotographic apparatuses such as a copy machine and a laser beam printer comprise a various types of rollers for developing electrostatic latent images formed on a photosensitive drum on a paper with a developer, and then fixing them. The developing part has the photosensitive drum and a roller for applying oil, which is not applicable to a dry-laid electrophotographic apparatus. The fixing part has a fixing roller and a pressure roller.
Conventionally, separation pawls are disposed on the photosensitive drum, and the fixing and pressure rollers to prevent the paper from winding the roller, which retards a smooth action. The separation pawls pick up a rim of the paper in a way that tips of the pawls are contacted with and rub an outer surface of the roller to prevent the paper from winding the roller.
A contact width of the separation pawls and the roller is about 1 to 10 mm. One roller generally has 4 to 16 separation pawls. Since the separation pawls contact locally with the roller, the roller is partially abraded, whereby no excellent image can be obtained. In addition, since the separation pawls also contact locally with the paper, the developer transferred to the paper is easily scraped off, and the developer scraped off is deposited on the separation pawls to contaminate the paper.
To address such problems, Japanese Laid-Open Patent Publication No. 59-188681 proposes a paper peeling apparatus capable of line-contacting with the roller.
Japanese Laid-Open Patent Publication No. 11-184300 proposes a peeling sheet obtained by laminating a heat-resistant plastic sheet or a metal sheet as a support with a fluororesin on one surface thereof, and folding it such that the fluororesin is to be outside.
When the support is the metal sheet, in many cases, the peeling sheet is adhered to the support member with an adhesive.
However, when the peeling sheet is adhered to the support with the adhesive, the peeling sheet is stripped off from the support under high temperature and for a long time, or a temperature cycle which increases and decreases the temperature repeatedly. Furthermore, it is difficult to coat the adhesive uniformly, and adhesion is different on portions. The peeling sheet is partially stripped off and waved. As a result, the peeling sheet becomes useless, and the paper cannot be peeled.
The paper peeling apparatus described in Japanese Laid-Open Patent Publication No. 59-188681 comprises a metal base plate, and a plastic plate, i.e., a fluororesin, having a thickness of 0.05 mm or more secured and support on the base plate. A tip of the plastic plate protruded slightly from the metal base plate is line-contacted with the fixing roller. The tip of the plastic plate is stripped off by plastic deformation, thus paper peeling ability is decreased.
The laminate obtained by folding the support with a fluororesin on one surface thereof such that the fluororesin is to be outside, described in Japanese Laid-open Patent Publication No. 11-184300, has the problem that curvature increases at cross-section of a contact surface of the fixing roller.
In recent years, the developer, i.e., a toner, for use in the electphophotograhic apparatus shifts to include a highly transparent polyester-based binder resin to improve color development. The toner including such polyester-based binder resin is extremely tackiness. If such toner is used in the paper peeling apparatus described in Japanese Laid-Open Patent Publication No. 59-188681, the toner is deposited on the metal base plate, and an adhered portion of the metal base plate and the plastic plate. If such toner is used in the peeling sheet described in Japanese Laid-Open Patent Publication No. 11-184300, it becomes difficult to line-contact with the fixing roller, and to peel off the paper.